Hydrocarbon gas was widely distributed in nature and had complex causes and sources. And the hydrocarbon gas can present the change of macroscopic and microscopic characteristics in different conditions of geological environment. According to that, the research of hydrocarbon gas should not be confined to the traditional energy minerals such as petroleum, natural gas, but need to promote to more other research areas. Based on the standardization of hydrocarbon gases in picrite, centering on the tin polymetallic deposit in Limu, Guangxi, this paper focused on the study of the macroscopic characteristics and microscopic laws of hydrocarbon gases in granite, orebody and surface soil at different periods of the mining area. Through research and comparison, this paper revealed the characteristics and variation rules of hydrocarbon gases in granites and different types of ores at different stages, and found out the fact that the maturity of hydrocarbon gases, which was influenced by mineralization, increased and migrated upward through tectonic fissures and was absorbed by the surface soil, which formed anomalies. The intrinsic genetic relationship and spatial correspondence between deep concealed ore body and soil hydrocarbon gas anomaly were clarified, and the characteristic indexes and parameters of hydrocarbon gas for judging the enrichment and mineralization of rare metal granite were established. The results showed that the research idea and method of taking the characteristics of hydrocarbon gas as the geochemical indicator for judging the enrichment and mineralization of rare metal granite was correct and feasible. And it would have a positive impact on the further development of hydrocarbon gas research and application in the future.